Device and Method for Ring Gate Closing Optimization

ABSTRACT

This invention discloses in particular an actuation cylinder ( 10 ) for controlling the movement of a ring-gate ( 40 ) of a hydraulic machine, said actuation cylinder ( 10 ) comprising a body ( 18 ) forming a first chamber ( 22 ) provided with a first duct ( 26 ) and a second chamber ( 24 ) provided with a second duct ( 28 ) which are designed to receive an actuating fluid through said first duct ( 26 ) and said second duct ( 28 ), said chambers being separated from one another by a piston ( 20 ) connected to an actuating rod ( 14 ) and able to move in said body in a first direction in which the volume of the second chamber increases while the volume of the first chamber decreases, and in a second direction in which the volume of the second chamber decreases while the volume of the first chamber increases, said piston being provided with a rod ( 30 ) connected in said second chamber to an area ( 20   b ) of the piston turned toward said second chamber, said area ( 20   b ) having a surface less than an area ( 20   a ) of the piston turned toward the first chamber.

TECHNICAL FIELD AND PRIOR ART

The invention relates to the field of hydropower industry.

A ring gate is an optional mechanical component of a turbine, pump orpump-turbine, used to isolate the machine from the upstream waterconduct in stopped conditions, in maintenance and in case of default ofwicket gate closure or main mechanical failure and able to cut off thepassing flow.

A ring gate is mainly a cylindrical shell which moves along itslongitudinal axis with a fixed stroke from an open to a closed positionand conversely.

The linear stroke of the cylindrical shell is appropriate to theturbine, pump or pump-turbine in which the ring gate is fitted.

A well-known solution to operate a ring gate is to use several hydrauliccylinders distributed around the circumference of one end of the ringgate, the axis of the hydraulic cylinders being parallel to thelongitudinal axis of the cylindrical shell.

The bodies of the hydraulic cylinders are supported by a stationary partof the turbine, pump or pump-turbine and the ends of the operating rodsof the hydraulic cylinders are attached to the circular edge of thecylindrical shell.

A digital and/or hydraulic system controls the simultaneous linearmovement of the operating rods of the hydraulic cylinders to move thecylindrical shell, without excessive swing and distortion in order toavoid jamming of the cylindrical shell in the stationary surroundingparts and damaging of the hydraulic cylinders, cylindrical shell andstationary parts.

Generally, the ring gate is “autoclave” or self-sealing and twodifferent pressure levels are used to operate cylinders.

-   -   a high-pressure level to open ring gate, because cylinders must        operate against the weight of ring gate and the differential        pressure between upstream and downstream pressure of the ring        gate when it is closed;    -   a low-pressure level to avoid risks of damaging parts in        downwards movement when the ring gate is closing, because the        ring gate closes naturally by its own weight and the low        pressure will help the closure in case of friction point and        will avoid mechanical damage by reducing the effort in case of        blocking by external element stuck up in the ring gate.

There is a need to reduce the forces or the efforts applied to thecylinders controlling the ring gate.

Prior art systems build two pressure levels from the hydraulic system.Different solutions are possible and request many components to buildthe two pressure levels, essentially by using two pressure tanks (oneper pressure level).

Those solutions are complicated, costly and requesting high level ofmaintenance.

SUMMARY OF THE INVENTION

The invention first concerns a cylinder comprising a body forming afirst chamber provided with a first duct and a second chamber providedwith a second duct which are designed to receive an actuating fluidthrough said first duct and said second duct, said chambers beingseparated from one another by a piston connected to an actuating rod andable to move in said body in a first direction in which the volume ofthe second chamber increases while the volume of the first chamberdecreases, and in a second direction in which the volume of the secondchamber decreases while the volume of the first chamber increases, saidpiston being provided with an additional element, for example a rod or acylinder, in said second chamber.

Said additional element is connected in said second chamber to an areaof the piston turned toward said second chamber, said area having asurface less than an area of the piston turned toward the first chamber.

Said additional member can be hollow, being just delimited by a wall.

In an actuation cylinder according to the invention, said additionalelement, for example said rod, extends above a top of said body througha watertight opening.

The invention also concerns a hydraulic system, which can be implementedin the control of the movement of a ring-gate of a hydraulic machine,said hydraulic system comprising at least one actuation cylinderaccording to the invention, and a same hydraulic circuit for feedingsaid first chamber through said first duct and said second chamberthrough said second duct with a fluid at a same pressure.

A cylinder according to the invention thus allows the use of onehigh-pressure level only for opening and closing, which decreases thehydraulic components number, increasing robustness and decreasing thecost of the whole system.

The invention also concerns a system for controlling the movement of aring gate, comprising a plurality of actuation cylinders, each accordingto the invention.

The invention also concerns a system for controlling the movement of aring gate, comprising a plurality of groups actuation cylinders, eachgroup comprising at least:

-   -   a first actuation cylinder according to the invention;    -   a second actuation cylinder comprising a body forming a first        chamber and a second chamber which are designed to receive an        actuating fluid, said chambers being separated from one another        by a piston connected to an actuating rod and able to move said        body in a first direction in which the volume of the second        chamber increases while the volume of the first chamber        decreases, and in a second direction in which the volume of the        second chamber decreases while the volume of the first chamber        increases;    -   a hydraulic synchronization member connecting said first chamber        of said first actuation cylinder and said second chamber said        second actuation cylinder.

The invention also concerns a hydraulic machine of the turbine, pump orpump-turbine type, comprising a runner and a ring gate able to movebetween a position of opening and a position of closing at least onechannel supplying said runner with water, and:

-   -   a plurality of actuation cylinders according to the invention,        each actuating rod being linked with said ring gate to move it        between said position of opening and said position of closing;    -   or a system according to the invention for controlling the        movement of said ring gate.

The invention also concerns a method of operating an actuation cylinderaccording to the invention, wherein a fluid with a predeterminedpressure (P) is fed to said first chamber through said first duct tomove said piston in said second direction and the same fluid with saidsame predetermined pressure (P) is fed to said second chamber throughsaid second duct to move said piston in said first direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a cylinder according to the invention;

FIG. 1B is a cross section of an additional element implemented in acylinder according to the invention;

FIG. 1C shows a cylinder according to the prior art;

FIG. 2 shows a view of ring gate and of its cylinders;

FIG. 3 shows a group of 2 cylinders connected as synchronizationmembers;

FIG. 4 shows a diagrammatic view of a ring gate and of 3 groups ofcylinders, each group comprising a cylinder according to the invention.

FIG. 5 is a cross-section of a hydraulic machine to which the inventioncan be applied.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

A cylinder 10 according to the invention is illustrated on FIG. 1A.

It comprises a body 18 forming a first chamber 22 and a second chamber24 which are each designed to receive and to evacuate an actuatingfluid, such as oil, through a duct 26, 28. Said chambers are separatedfrom one another by a piston 20. The piston is connected to an actuatingrod 14, which itself is to be connected to a ring gate for actuating itbetween its open and its closed position. First chamber 22 is situatedon the side of the rod relative to piston 20, second chamber 24 beingsituated on the side opposite the rod relative to piston 20.

Ducts 26, 28 are for connecting each chamber to a hydraulic circuitcomprising fluid pressurizing means, for example at least one pump, andto a source of actuating fluid. A control unit controls the actuation ofthe hydraulic circuit including the fluid pressurizing means. Saidcontrol unit can for example comprise a processor or a microprocessor,or an electric or electronic circuit capable of implementing or beingprogrammed to actuate the hydraulic circuit.

Said piston 20 is able to move in the body in a first direction I inwhich the volume of the second chamber 24 increases while the volume ofthe first chamber 22 decreases, and then in a second direction II inwhich the volume of the first chamber 22 increases while the volume ofthe second chamber 24 decreases.

Piston 20 has two areas 20 a and 20 b, each perpendicular to directionsI and II which are designated “lower piston area” and “upper pistonarea” and respectively situated on the side of the actuating rod 14 andon the opposite side. A cylinder 10 can be used in any position and the“lower” and “upper” designations should not be interpreted as limitingfeatures of the invention.

Upper piston area 20 b is exposed to pressure P to move the piston 20 insaid first direction I (when connected to a ring gate, said movement insaid first direction I is for closing the ring gate).

Lower piston area 20 a is exposed to pressure to move the piston 20 insaid second direction II (when connected to a ring gate, said movementin said second direction II is for opening the ring gate).

The second chamber 24 comprises an additional element 30, for example arod, connected to said upper area 20 b. Said additional element 30 isnot mechanically connected to any actuating mechanism. It moves togetherwith piston 20.

This additional element 30 reduces the surface S of piston area 20 bexposed to pressure P: in particular, the upper piston area 20 b has asurface less than the surface of the lower piston area 20 a; thecorresponding force F applied to said upper piston area 20 b indirection I is also reduced (due to the relation P=F/S) in comparison toa cylinder—like on FIG. 1B—in which no additional element 30 isimplemented. For example, if said element 30 is a rod, the value of theeffort is adjusted by the diameter of said rod.

As a result a same pressure P can be applied to the upper chamber 24when piston 20 is moved in the body in first direction I and to thelower chamber 22 when piston 20 is moved in the body in second directionII: said same pressure will result in different forces or effortsapplied to the upper piston area 20 b and to the lower piston area 20 a.

A same hydraulic circuit 50 (FIG. 1A) can therefore be implemented tofeed both chambers with a same fluid at the same pressure P, thisachieving considerable savings in pumps, tanks, valves . . . etc.Through a valve 51, the same hydraulic circuit 50 is connected either toduct 28 (thus feeding upper chamber 24 with a fluid at pressure P) or toduct 26 (thus feeding lower chamber 22 with said same fluid at the samepressure P).

This also reduces the amount of actuating fluid used to control amovement of the piston 20 which means that the hydraulic circuitconnected to duct 28 is simplified.

The height h of the additional element 30 is slightly higher than theheight of the ring gate or the stroke of the rod.

Element 30 extends beyond the top portion 21 of body 18; when it is inits lowest position in the cylinder it can also extend beyond the top 21or be flush with it. An opening in said top portion is made so thatelement 30 can move upwards and downwards together with piston 20. Saidopening is watertight (for example with a joint 23) so that element 30can move upwards and downwards without any loss of fluid.

Preferably, the additional element 30 has a circular cross section in aplane perpendicular to any of directions I or II. But other shapes ofsaid cross section can also be implemented. It is for example acylindrical rod, preferably hollow, which results in less weight FIG. 1Bshows a cross section, in a plane perpendicular to any of directions Ior II, of such an empty rod, reference 31 designating its wall whichdelimits a hollow internal space 33.

The width d of said cross section (which is a diameter in case of acircular cross section) is calculated depending on the force F whichmust be applied when actuating piston 20 in direction I.

Closing a ring gate connected to actuating rod 14 is facilitated by theweight of the ring itself but a force must be applied to area 20 b inorder to control the movement of the rod 14, in particular so that isdoes not buckle. As explained above, using a cylinder 10 according tothe invention, this can be achieved with a same pressure as upon openingthe ring gate.

A cylinder 10′ according to the prior art is illustrated on FIG. 1C. Itbears the same reference numbers as FIG. 1A provided with a “′”. Thearea 20 b′ bears no additional element 30 in the second chamber 24′ andthe surface of area 20 b′ is larger than surface of area 20 a′. Thus,for a same pressure P applied to area 20 b′ and to area 20 b (FIG. 1A),the force which must be applied when moving piston 20′ in the firstdirection I is more important than the force applied to piston 20 ofFIG. 1A when it is moving in the same first direction. This shows thatdifferent pressures P′₁, P′₂, requiring different hydraulic systems50′₁, 50′₂ (see FIG. 1C) must be used in both directions whenimplementing a cylinder according to the prior art.

FIG. 2 illustrates how several cylinders 10 a, 10 b, . . . according tothe invention can be connected (through their actuating rods not shownon the figure) to a ring gate 40, at a plurality of locations around itsperimeter. A ring gate 40 has a diameter which is for example between 2m and 15 m. It is for example made of steel. FIG. 5 shows how eachcylinder 10 can be connected to a ring gate 40, as well as other partsof a hydraulic machine.

According to US 2013/0098237, a system to control the actuation of aring gate can comprises several groups of cylinders, each groupcomprising at least 2 cylinders, the cylinders of a same group beingconnected by at least one synchronization member.

A cylinder according to the invention can be used in such a group ofcylinders. FIG. 3 shows a group of 2 cylinders 10, 10′, of whichcylinder 10 is a cylinder according to the invention, cylinder 10′having a structure according to FIG. 1C. The first chamber 22 ofcylinder 10 is connected by a duct 32 to the second chamber 24′ ofpiston 20′ of cylinder 10′. Preferably, the area 20 a of piston 20 ofcylinder 10 is approximately equal to the area 20 b′ of piston 20′ ofcylinder 10′. Reference 40 designates the ring to which the actuatingrods 14, 14′ are connected.

The element 30 reduces the force necessary to control the movement ofboth cylinders 10, 10′, the pistons 20, 20′ moving in a same directionat the same time.

As illustrated on FIG. 4, 3 such groups 10, 10′, 11, 11′, 12, 12′ ofcylinders are located on the perimeter C of a ring gate 40, twoconsecutive locations corresponding to cylinders belonging to differentgroups, two cylinders of same group being disposed diametricallyopposite on the perimeter of the ring. Cylinders 10, 11, 12 arecylinders according to the invention (FIG. 1A), each including anadditional element 30 in its second chamber, cylinders 10′, 11′, 12′being cylinders according to FIG. 1C, not having such an additionalelement.

Examples of hydraulic circuits to control the different groups ofcylinders are given in US 2013/0098237.

In a variant, as explained in US 2013/0098237, the cylinders 10, 10′ ofa same group have approximately the same dimensions

As shown in FIG. 5, a hydraulic machine 100, which may be of theturbine, pump, or paddle wheel pump type, implementing the inventioncomprises a paddle wheel 52, the ring gate 40 and several actuatingcylinders 10 (of which only one is visible on FIG. 5) according to theinvention. The ring gate 40 is movable along a direction Y, between anopen position and a blockage position (which is illustrated on FIG. 5)of a water supply channel 58 of the paddle wheel. The ring gate 40 isinstalled between fixed guide vanes 42 and movable wicket gates 41 usedto orient the flow of water toward the paddle wheel.

1. An actuation cylinder (10) for controlling the movement of aring-gate (40) of a hydraulic machine, said actuation cylinder (10)comprising a body (18) forming a first chamber (22) provided with afirst duct (26) and a second chamber (24) provided with a second duct(28) which are designed to receive an actuating fluid through said firstduct (26) and said second duct (28), said chambers being separated fromone another by a piston (20) connected to an actuating rod (14) and ableto move in said body in a first direction in which the volume of thesecond chamber increases while the volume of the first chamberdecreases, and in a second direction in which the volume of the secondchamber decreases while the volume of the first chamber increases, saidpiston being provided with a rod (30) connected in said second chamberto an area (20 b) of the piston turned toward said second chamber, saidarea (20 b) having a surface less than an area (20 a) of the pistonturned toward the first chamber. 2-9. (canceled)